Safes, vaults, lockers, and keyless entries, among other types of secure systems, use locks requiring a unique combination for access. Typically, the combination is a set of numbers and rotational sequences which align tumblers to a predetermined orientation. The tumblers make a sound when dropping and this “signature” can reveal the combination when sophisticated listening devices are used. Furthermore, telltale wear patterns can develop with mechanical abrasion and can similarly be detected with sensitive equipment.
One method of eliminating the mechanical action of tumblers is to use an optical alignment system. U.S. Patent Application 2206/0037374 to Skelly teaches the use of a light beam received by a sensor through aligned holes in three concentric tubes rotating about the common axis. The tubes can be manipulated by interfacing members on each tube such that a series of discrete rotations of the innermost tube, twisting clockwise and counterclockwise, bring the three into an alignment of the holes. The aligned holes enable a beam originating in the center to pass through to a sensor located outboard. The receipt of the beam passes a command to an unlocking mechanism. There are no tumblers to drop and no sound clues to witness the angular settings of the combination.
Similarly, in U.S. Pat. No. 2,008,150 to Nelson, a light signal traversing a “fence” of aligned holes in a series of disks mounted on a common shaft provides the means for controlling a lock. The combination is the individual orientation of each disk thus aligned. Except for one disk corresponding to a dial, the disks are free to rotate on the shaft, and in like manner to Skelly, each can be set into position by means of rotating the dial and engaging an interfacing geometry. The problem with such a system, however, is that the subsequent rotation of the moving part could disturb the prior setting of a positioned part. The common shaft, the case of Nelson, or the nested tubes, in the case of Skelly, would inevitably create rotational drag on co-journaled elements. What is missing in the prior art is a light fence where each disk can be individually set and registered to position.
The energy source for such opto-electrical systems is typically supplied by battery. If the light is rendered always on, or if it is switched on to initialize the combination setting procedure, battery life will be consumed and ultimately require service. The benefit in safety attendant to such an optical device is thus offset by the inconvenience of maintenance. It would be an advantage, therefore, to provide for conservation of energy use and extended battery life in the design of such systems.
Both Skelly and Nelson use number indices to orient the combination. Even if security breach were not a risk, number patterns are not particularly user-friendly. They can be hard to remember, especially if they are randomly chosen and not resettable in after-market use. Research has shown that visual patterns are processed in the brain in a different way than word or number patterns. Not only is visual recognition instantaneous, it is also easier to remember. Furthermore, visual patterns do not lend themselves to discovery by guessing, in the way that knowledge of an individual's background can sometimes suggest a number combination. Some means to set a visual pattern combination, therefore, would represent a needed improvement.